Sound Capture - Sensitivity

Learning Outcomes

  • Define microphone sensitivity and explain why it affects sound capture.
  • Compare the sensitivity of condenser and dynamic microphones in practical recording situations.
  • Explain how sensitivity links to gain staging, noise floor, clipping and overload.
  • Choose suitable microphones and settings for quiet, detailed and loud sources.
  • Describe how pad switches, phantom power and mic distance affect capture quality.
  • Apply sensitivity knowledge to Component 1 recording decisions and written explanations.

Edexcel A-Level Music Technology (9MT0) Syllabus

For Component 1: Recording, you need to show that you can capture sounds accurately using suitable music technology equipment. Sensitivity is part of that decision-making: it affects microphone choice, placement, gain setting, noise, distortion and how much detail is recorded. You may need to explain these choices in your production notes and apply the same knowledge when analysing recording equipment settings in exam-style contexts.

  • Select microphones that suit the sound source and recording purpose.
  • Understand why condenser microphones are often used for detailed studio capture.
  • Recognise why dynamic microphones can be suitable for loud sources.
  • Use input gain correctly to avoid noisy or distorted recordings.
  • Understand when a pad switch can prevent overload.
  • Consider how mic distance changes the balance of direct sound, room sound and spill.
  • Link technical decisions to audible outcomes, such as clarity, hiss, clipping or loss of detail.

Test Your Knowledge

Attempt these questions before reading this article. If you find some difficult or cannot remember the answers, look more closely at that area during your revision.

  1. What does microphone sensitivity describe?
  2. Why are condenser microphones usually better than dynamic microphones for quiet, detailed sources?
  3. What problem might occur if a very sensitive microphone is placed close to a loud drum or guitar amplifier?
  4. How can a pad switch help when recording a loud source?
  5. Why might a low-sensitivity microphone require more preamp gain?

Introduction

Sensitivity is one of the most practical microphone specifications for recording. It describes how much electrical output a microphone produces from a given sound pressure. In simple terms, a more sensitive microphone produces a stronger signal from the same sound source than a less sensitive microphone. This matters because a strong, clean signal is easier to record without excessive gain, hiss or noise.

In Component 1, sensitivity affects real recording decisions: whether a condenser is suitable for a vocal, whether a dynamic microphone can handle a close snare drum, whether the input gain is too high, and whether the recording captures detail or becomes harsh and distorted. Good sound capture is not just about choosing a famous microphone; it is about matching the microphone’s behaviour to the performer, instrument, room and recording level.

Key Term: Sensitivity
A measure of how much electrical signal a microphone produces for a given sound pressure level.

What Microphone Sensitivity Measures

A microphone changes acoustic energy into an electrical signal. Sensitivity describes the size of that output signal when the microphone receives a standard sound pressure. Manufacturers often state microphone sensitivity in millivolts per Pascal, written as mV/Pa, or as a decibel value relative to a reference level. You do not need to memorise lots of manufacturer figures for Component 1, but you should understand the practical meaning: higher sensitivity means more output for the same sound.

For example, if two microphones are placed the same distance from a singer and the singer performs at the same volume, the more sensitive microphone will send a stronger signal to the preamp or audio interface. This can be useful because the preamp does not need to add as much gain. Less gain can mean less electronic noise, especially if the audio interface or mixer preamps are not high quality.

Key Term: Sound Pressure Level
A measurement of the physical pressure variation caused by sound, usually expressed in decibels SPL.

Key Term: Pascal
A unit of pressure used in microphone sensitivity measurements; 1 Pascal is commonly used as a reference sound pressure.

Sensitivity is not the same as “quality”. A high-sensitivity microphone is not automatically better, and a low-sensitivity microphone is not automatically worse. Sensitivity only tells you about output level. Tone, frequency response, polar pattern, transient response, self-noise, maximum SPL handling and placement all affect the final recording.

For exam work, avoid saying “this microphone is better because it is more sensitive” unless you explain why that helps in the specific context. A more sensitive microphone may be excellent for a quiet acoustic guitar but problematic if placed very close to a loud snare drum without a pad or suitable gain setting.

Test Tip: When explaining sensitivity, link the technical point to an audible result. For example: “The condenser’s higher sensitivity helps capture the quiet detail of the vocal breath and finger noise, while requiring less preamp gain.”

Condenser and Dynamic Microphones

The most common sensitivity comparison in A-Level recording is between condenser and dynamic microphones. Condenser microphones are generally more sensitive than dynamic microphones. They usually capture more detail from a sound source and are well suited to quieter or more detailed material. This is why they are often used for vocals, acoustic guitar, piano, orchestral instruments, drum overheads, small percussion and ambient recording.

Condenser microphones require power to operate. This is usually supplied as phantom power from a mixing desk or audio interface, although some condenser microphones can use batteries. Their high sensitivity is partly linked to their construction: the diaphragm is light and responds quickly to sound waves. This helps with transient detail and high-frequency capture, especially in small-diaphragm condenser microphones.

Key Term: Condenser Microphone
A microphone type that uses a charged capsule and requires power, usually phantom power, and is often valued for sensitivity and detail.

Key Term: Phantom Power
A DC voltage, commonly supplied by a mixer or audio interface, used to power many condenser microphones.

Dynamic microphones usually have lower sensitivity. They tend to need more preamp gain to reach the same recording level as a condenser. However, this can be useful for loud sources because the microphone is less likely to produce an excessively hot signal. Dynamic microphones are often chosen for close-miked drums, guitar amplifiers and live vocals because they can usually cope well with high sound pressure levels and rougher handling.

A lower-sensitivity dynamic microphone may not capture as much quiet detail as a condenser, but that is sometimes an advantage. On a snare drum, for example, you may not want the microphone to pick up every cymbal reflection or room sound. On a loud guitar cabinet, a dynamic microphone can capture a focused, controlled sound without being too revealing of unwanted room tone.

Key Term: Dynamic Microphone
A microphone type that uses electromagnetic induction, usually with lower sensitivity than a condenser and often suited to loud sources.

Ribbon microphones are another type you may encounter. Traditional ribbon microphones often have low output and need plenty of clean gain, although active ribbon designs can have higher output. They can sound smooth and natural but may be more delicate than typical dynamics. If you mention ribbon microphones in an answer, keep the point relevant and avoid generalising too far.

A major exam skill is recognising that microphone type, sensitivity and source level work together. A condenser on a vocal might be ideal because it captures subtle articulation and breath detail. The same condenser placed extremely close to a loud trumpet bell, kick drum or overdriven guitar speaker could overload the microphone’s electronics or the preamp if gain is not set carefully.

Sensitivity, Gain Staging and Noise

Sensitivity becomes most useful when you connect it to gain staging. Gain staging means setting suitable levels at each point in the recording chain: microphone, preamp, audio interface, DAW channel and any later processing. The aim is to record a healthy signal that is neither too quiet nor distorted.

Key Term: Gain Staging
The process of setting suitable signal levels through each part of the recording chain to avoid noise and distortion.

A low-sensitivity microphone produces a smaller signal. To record it at a suitable level, you turn up the preamp gain. If the preamp is clean and has enough gain available, this can work perfectly well. If the preamp is noisy, raising the gain can make hiss or electronic noise more noticeable. This is especially likely when recording quiet sources such as soft vocals, fingerpicked guitar, distant percussion or quiet room ambience.

Key Term: Noise Floor
The level of unwanted background noise in a recording system, such as hiss, hum or room noise.

A high-sensitivity microphone produces a stronger signal. This can reduce the amount of preamp gain needed, which can help achieve a cleaner recording of quiet detail. However, a strong output can also cause problems if the source is loud or very close to the microphone. The preamp input may clip, or the microphone’s internal electronics may overload. This produces harsh distortion that cannot be fully repaired later.

Key Term: Clipping
Distortion caused when a signal exceeds the maximum level that a device can handle.

A pad switch is used to reduce the level before it reaches the next stage of the chain. Many condenser microphones include a pad, often reducing the signal by 10 dB or 20 dB. This is useful when the microphone is suitable in tone and polar pattern but the output level is too high for the source. For example, a condenser used as a drum overhead or close to a loud brass instrument may need its pad engaged to avoid overload.

Key Term: Pad Switch
A switch that reduces a microphone or input signal by a fixed amount, often 10 dB or 20 dB, to help prevent overload.

Exam Warning: Do not confuse sensitivity with gain. Sensitivity is a property of the microphone. Gain is the amount of amplification added by the preamp, mixer or interface.

A good recording level should leave headroom. In digital recording, clipping above 0 dBFS produces unpleasant distortion. When recording for coursework, it is better to leave space for sudden peaks than to record too hot. A vocal performance may be quiet in the verse and much louder in the chorus; a drummer may hit harder during a take than during soundcheck. Sensitivity affects how quickly these peaks reach the input limit.

Key Term: Headroom
The safety margin between the normal operating level and the point where clipping or overload occurs.

Matching Sensitivity to Real Recording Sources

For vocals, a condenser microphone is often a strong choice because it captures detail, brightness and articulation. Its high sensitivity helps record soft phrases without needing excessive preamp gain. However, the placement must be controlled. A pop shield helps protect the microphone from plosives and moisture, and the singer should not be so close that the capsule overloads or low frequencies become too strong. Condenser microphones can be sensitive to moisture, so care is needed with singers and brass players.

If the singer is very loud, a dynamic microphone can also be suitable. It may give a more controlled sound, reduce room pickup and handle high levels well. In a less treated room, a dynamic’s lower sensitivity and close placement can help reduce unwanted reflections, though polar pattern and distance matter too.

For acoustic guitar, condenser microphones are often useful because they capture the transient detail of the pick or fingers and the high-frequency sparkle of the strings. A small-diaphragm condenser can work well because of its fast response. If the recording sounds noisy, check whether the source is too far away, the room is too loud, or the preamp gain is too high. Moving the microphone slightly closer can raise the direct sound level, but placing it too close to the sound hole can make the tone boomy.

For piano, condensers are also common because the instrument has a wide frequency range and many subtle details. A more sensitive microphone can capture both quiet passages and the resonance of the instrument. The challenge is leaving enough headroom for loud chords. Piano dynamics can vary greatly, so gain must be set while the player performs the loudest section.

For drums, sensitivity choices are more varied. Close microphones on snare and toms are often dynamic because the source is loud and spill is a problem. Condensers are often used as overheads because they capture cymbal detail and the overall image of the kit. Since condensers are sensitive, placement and gain are vital. The further a microphone is from the drum kit, the more room sound and spill it captures. The closer it is to one drum, the more focused the sound, but the tone can become less natural and proximity effect may increase low frequencies.

Key Term: Spill
Unwanted sound from other instruments or parts of a kit being picked up by a microphone.

For ambient recording, sensitivity is useful because the microphone may be placed further from the source. Condenser microphones are well suited to this because they can capture quieter reflected sound and room detail. In a good acoustic space this can add realism and depth. In a poor room, the same sensitivity may reveal unwanted reflections, noise, computer fans or traffic. In Component 1, this means you should only choose ambient techniques when the room sound improves the recording.

For loud guitar amplifiers, a dynamic microphone is often a safe choice. It can be placed close to the speaker and can usually handle high SPL. A condenser can be used if the sound suits the production, but it may need distance, careful gain setting or a pad. If the recording sounds fizzy, harsh or distorted, check whether the amp tone itself is harsh, the microphone is placed too close to the centre of the speaker, or the input is overloading.

For DI keyboard capture, microphone sensitivity is not involved because the sound is taken directly from the keyboard output through a DI box or audio interface. This is a useful comparison for exam answers: sensitivity applies to microphones responding to acoustic sound pressure, not to MIDI programming or line-level keyboard outputs.

Test Tip: In your recording log or evaluation, write about sensitivity through decisions and outcomes: “I used a condenser for the acoustic guitar because its higher sensitivity captured finger detail, but I reduced the input gain to leave headroom for louder strums.”

Sensitivity, Distance and Polar Pattern

Sensitivity does not work in isolation. Distance from the source changes the level reaching the microphone. A quiet source recorded far away may need a sensitive microphone and more gain. A loud source recorded close may overload even a good microphone if the gain is too high.

As the microphone moves further from the source, the direct sound becomes quieter relative to the room sound. This means the recording may contain more reverb, reflections and spill. Close miking reduces room sound but can create other problems, such as proximity effect on directional microphones or an unnatural tone from capturing only one part of an instrument.

Polar pattern also affects how useful a sensitive microphone will be. A cardioid condenser may capture detailed sound from the front while rejecting some sound from the rear. This can be useful for vocals or acoustic guitar in a studio. A wider pattern or more distant placement may capture more room sound. For Component 1, you should be able to explain why this is desirable or undesirable in context.

Key Term: Polar Pattern
The directional pickup shape of a microphone, describing where it captures sound most strongly.

A cardioid microphone has strong front pickup, reduced side pickup and minimal rear pickup. This can reduce unwanted room sound compared with less directional patterns. Because sensitivity may reveal low-level details, using a suitable polar pattern can help control what the microphone captures.

The best approach is to listen critically, then adjust. If the recording is too noisy, try improving the source level, moving the microphone closer, reducing room noise, or using a more sensitive microphone. If the recording distorts, reduce preamp gain, engage a pad, move the microphone further away, or choose a microphone better suited to high SPL.

Key Point Checklist

This article has covered the following key knowledge points:

  • Microphone sensitivity describes output level for a given sound pressure.
  • Higher sensitivity gives a stronger signal from the same source.
  • Sensitivity is not the same as sound quality.
  • Condenser microphones are generally more sensitive than dynamic microphones.
  • Condensers are often suitable for vocals, acoustic guitar, piano, overheads and ambient recording.
  • Dynamic microphones are often suitable for loud close-miked sources such as drums and guitar amplifiers.
  • Low-sensitivity microphones may require more preamp gain, which can raise audible noise.
  • High-sensitivity microphones can overload on loud sources if gain and placement are not controlled.
  • A pad switch reduces signal level, commonly by 10 dB or 20 dB.
  • Good gain staging leaves headroom and avoids clipping.
  • Microphone distance affects direct sound, room sound and spill.
  • Sensitivity should be explained in relation to audible recording outcomes.

Key Terms and Concepts

  • Sensitivity
  • Sound Pressure Level
  • Pascal
  • Condenser Microphone
  • Phantom Power
  • Dynamic Microphone
  • Gain Staging
  • Noise Floor
  • Clipping
  • Pad Switch
  • Headroom
  • Spill
  • Polar Pattern